Certified paper and an apparatus for discriminating the genuineness thereof

ABSTRACT

A discriminating apparatus is provided with a first light detecting element ( 521 ) for detecting a light emitted from a luminescent ink of a security mark upon being placed in a specified environment, a second light detecting element ( 531 ) for detecting a reflected light from a nonluminescent ink of the security mark, the first and second light detecting elements ( 521, 531 ) being so arranged as to detect the lights from the same position of a bank note (M), a third light detecting element ( 522 ) for detecting a light emitted from the monitor mark (M 4 ), a light intensity comparing means ( 80   a ) for comparing a light intensity detected by the third light detecting element ( 531 ) with a preset reference light intensity to calculate a deviation from the reference light intensity, a light intensity converting means ( 80   b ) for converting an output value from the first light detecting element ( 521 ) into a corrected output value corresponding to the deviation, and a genuineness discrimination means ( 80   c ) for discriminating the genuineness of the bank note (M) base on the corrected output value. Accordingly, genuineness can be securely discriminated even if a printed state of the luminescent ink on the bank note or other certified paper varies.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

[0001] This invention relates to a discriminating apparatus capable ofdiscriminating genuineness of various certified papers including, forexample, bank notes, securities such as stocks and various othercertified documents such as slips at a higher reliability.

[0002] There have been conventionally known discriminating apparatusesfor discriminating genuineness of bank notes, securities or likecertified papers. Such discriminating apparatuses discriminategenuineness of certified paper by photoelectrically scanning characters,figures, symbols, or (hereinafter referred to collectively as “printedmarks”) printed in specified positions of the paper, and comparing ascanned pattern with a prestored pattern of the genuine certified paper.

[0003] However, improved forging technology has made it difficult todiscriminate forged certified paper from genuine certified paper onlybased on usual printed patterns. German Patent Publication DE 197 085 43A1 discloses printing of bank notes with a luminescent ink containingelectroluminescent material which emits a light upon application ofultraviolet rays or an alternating voltage. The use of such anelectroluminescent ink makes the certified paper luminous uponprojection of ultraviolet rays or upon being placed in analternating-current electromagnetic field and accordingly enablesdiscrimination of genuineness of certified paper by detecting thepresence or absence of the luminous light, even if the printed patternsmade on the genuine and counterfeit certified papers by usual printingcoincides with that of the genuine.

[0004] It could be seen, however, that if counterfeit bank notes shoulduse the above luminescent ink, the discrimination of genuineness becomesmore difficult. In particular, it is easy to forge an electroluminescentpattern similar to that of the genuine certified paper by spraying andadhering the electroluminescent material to the surface of the paperbecause the electroluminescent material is comprised of ultrafineparticles. Accordingly, discrimination of genuineness cannot be made forthe paper having the pattern of the electroluminescent by such anoperation even if the electroluminescent is made luminous in analternating-current electromagnetic field. The same applies to otherluminescent inks other than the electroluminescent.

[0005] In order to solve the above problem, genuineness may bediscriminated by detecting lights from both a printed mark made of theluminescent ink and the one made of the usual ink and discriminating thepresence of a specified correlation between the detected values or bycomparing the detected value of the printed mark made of the luminescentink with a reference value corresponding to a printed mark made on agenuine certified paper. However, even with such discrimination, thedegree of light emission may differ in the same environment of thealternating-current electromagnetic field due to different printedpositions of particularly the luminescent ink and different printedstates even in the same printing position from printing apparatus toprinting apparatus. This presents a new problem of a reduced precisionof genuineness discrimination.

[0006] In view of the above problems residing in the prior art, anobject of the present invention is to provide a certified paperdiscriminating apparatus capable of securely discriminating genuinenesseven if the printed state of a luminescent ink on certified papersvaries.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to a certified paper on which asecurity mark is printed using both a luminescent ink which emits alight upon being placed in a specified environment and a usualnonluminescent ink, and/or a monitor mark used to monitor a printed toneof the security mark is printed in vicinity of the security mark usingthe luminescent ink.

[0008] With such an inventive certified paper, by scanning the monitormark emitting a light in the specified environment when letting aspecified certified paper discriminating apparatus in which a referencelight intensity is stored beforehand scan the security mark of thecertified paper, the printed tone of the security mark can be known by acomparison of the light intensity of the scanned monitor mark with thereference light intensity. Thus, a correction can be made based on thecomparison result of the scanned security mark, with the result thatdata on the intensities of the lights from the security mark can bestandardized.

[0009] Accordingly, an inconvenience residing in the prior art thatprecision of discrimination of the certified paper based on the varyinglight intensity data from the scanned security mark is lower due to sucha variation can be solved, thereby improving precision in discriminatingthe genuineness of the certified paper.

[0010] The present invention is also directed to a certified paperdiscriminating apparatus for discriminating the genuineness of thecertified paper according to claim 1 by scanning the certified paper inan extending direction of the monitor mark, comprising a first lightdetecting means for detecting a light emitted from the luminescent inkof the security mark upon being placed in the specified environment; asecond light detecting means for detecting a reflected light from thenonluminescent ink of the security mark, the first and second lightdetecting means being so arranged as to detect the lights from the sameposition of the certified paper, a third light detecting means fordetecting a light emitted from the monitor mark; a light intensitycomparing means for comparing a light intensity detected by the thirdlight detecting means with a preset reference light intensity tocalculate a deviation from the reference light intensity; a lightintensity converting means for converting an output value from the firstlight detecting means into a corrected output value corresponding to thedeviation; and a genuineness discriminating means for discriminating thegenuineness of the paper based on the corrected output value.

[0011] With the discriminating apparatus thus constructed, the monitormark made of the luminescent ink of the certified paper fed into thediscriminating apparatus emits a light upon being placed in thespecified environment, and this light emission is detected by the thirdlight detecting element. The light intensity corresponding to themonitor mark detected by the third light detecting element is comparedwith the reference light intensity set beforehand to calculate thedeviation by the light intensity comparing means, and the output valuefrom the first light detecting element is converted into the correctedoutput value corresponding to the deviation based on the calculationresult by the light intensity converting means. The genuineness of thecertified paper is discriminated based on the corrected output value bythe genuineness discriminating means.

[0012] In this way, prior to discrimination of the genuineness of thecertified paper, an electrical signal representing a standard densityobtained by correcting the density of the luminescent ink of the printedmonitor mark is sent to the genuineness discriminating means, which thenmakes a specified genuineness discrimination. Thus, such aninconvenience that different printed states of the luminescent ink onthe certified papers influence a result of genuineness discriminationcan be solved, thereby constantly realizing a proper genuinenessdiscrimination.

[0013] The specified environment where the luminescent ink emits a lightmay be an environment of an alternating-current electromagnetic field ora light irradiating environment where infrared rays, ultraviolet raysand usual visible rays within a specified wavelength range areirradiated.

[0014] Preferably, the specified environment is an environment of analternating-current electromagnetic field created upon application of analternating voltage and the luminescent ink preferably has anelectroluminescent property of emitting a light in the environment ofthe alternating-current electromagnetic field.

[0015] With such an arrangement, the luminescent ink is nonluminescentand colorless in a usual environment since it emits a light in theenvironment of the alternating-current electromagnetic field. Thus, thecertified papers can be normally used without any trouble while theluminescent ink effectively performs its function in discriminatinggenuineness.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a perspective view showing one embodiment of a certifiedpaper discriminating apparatus according to the present invention in astate where a lid of a casing is closed,

[0017]FIG. 2 is a perspective view of the certified paper discriminatingapparatus of FIG. 1 in a state where the lid of the casing is open,

[0018]FIG. 3 is an exploded perspective view showing one embodiment ofan apparatus main body contained in the casing,

[0019]FIG. 4 is a perspective view showing the assembled apparatus mainbody of FIG. 3,

[0020]FIG. 5 is a section along A-A of FIG. 4,

[0021]FIG. 6 is a section along B-B of FIG. 4,

[0022]FIG. 7 is a perspective view showing an exemplary printed state ofa bank note,

[0023]FIG. 8A is an enlarged section along C-C of FIG. 7,

[0024]FIG. 8B is an another embodiment of an enlarged section of FIG.7,essentially FIG. 8A with M4 monitor mark elided.

[0025]FIG. 8C shows a state where printing is made by a mixed inkobtained by mixing the electroluminescent ink with the usualnonluminescent ink.

[0026]FIGS. 9A and 9B show changes of output values in proportion toamounts of light detected by first and second light detecting elementsduring scanning by a light detecting device with the lapse of time,wherein FIG. 9A is a partial enlarged view of the bank note M and FIG.9B is graphs showing changes of the output values of the

[0027] a storage means for storing reference data to be compared withthe output values of said first and said second light detecting means todiscriminate genuineness of said certified papers,

[0028] a comparing means for comparing the output values of said firstand said second light detecting means with a stored reference data;

[0029] and a genuineness discriminating means for discriminatinggenuineness of said certified papers based on a calculation result ofthe correlation calculating means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0030]FIGS. 1 and 2 are perspective views showing one embodiment of acertified paper discriminating apparatus according to the presentinvention, wherein FIG. 1 shows a state where a casing lid is closed andFIG. 2 shows a state where the casing lid is open. FIG. 3 is an explodedperspective view showing one embodiment of an apparatus main bodyprovided in a casing, and FIG. 4 is a perspective view showing theassembled apparatus main body. FIG. 5 is a section along A-A of FIG. 4,and FIG. 6 is a section along B-B of FIG. 4. It should be noted that, inFIGS. 1 to 4, directions of X-X, Y-Y, −X, +X, −Y and +Y are referred toas widthwise, forward and backward, leftward, rightward, forward andbackward directions.

[0031] The certified paper discriminating apparatus 1 according to thisembodiment discriminates genuineness of bank notes (certified papers) onwhich characters, figures or symbols are printed using both anelectroluminescent ink which emits a light upon being placed in anenvironment of an alternating-current electromagnetic field and a usualprinting ink. Particularly, the apparatus 1 is adapted to discriminatethe genuineness of a bank note M on which a security mark is printed ina specified position for the genuineness discrimination using both inksand a monitor mark used to monitor a printed state of the inks isprinted near the security mark using the luminescent ink.

[0032] In order to perform the above discrimination, a first, a secondand a third detecting constructions 71, 72, 73 to be described later areprovided in the discriminating apparatus 1. The first detectingconstruction 71 is adapted to detect an electroluminescent lightemission in an environment of an alternating-current electromagneticfield, and the second detecting construction 72 is adapted to detect areflected light from the usual ink. Further, the third detectingconstruction 73 is adapted to detect a printed state (density degree) ofthe luminescent ink.

[0033] As shown in FIGURES, an apparatus main body 2 and a control unit8 are contained in a box-shaped casing 9 in the discriminating apparatus1. The casing 9 is comprised of a rectangular parallelepipedic casingmain body 91 and a lid 92; provided atop the casing main body 91.

[0034] A pair of brackets 93 extending in forward and backwarddirections are provided at the opposite sides of the upper surface ofthe casing main body 91 with respect to its widthwise direction. The lid92 is made displaceable between a closing position shown in FIG. 1 whereit is placed on the casing main body 91 and an exposing position shownin FIG. 2 where it stands at the rear end of the casing main body 91 byrotatably supported about a horizontal axis 94 while having its rear endtightly held between the pair of brackets 93.

[0035] With the lid 92 in its closing position, a note transport path 95is defined between the upper surface of the casing main body 91 and thelower surface of the lid 92 as shown in FIG. 1. When a bank note M isinserted into the note transport path 95 from the front side of thecasing 9, an unillustrated sensor detects it and a driving mechanism isdriven in accordance with a drive signal from the control unit 8 sent inresponse to a detection signal of the sensor to pull the bank note Minto the note transport path 95. Whether or not the inserted bank note Mis genuine is discriminated by a discriminating mechanism (first andsecond detecting constructions 71 and 72) contained in the apparatusmain body 2 as described later.

[0036] A plurality of guide projections 95 a elongated in forward andbackward directions are formed on the upper surface of the casing mainbody 91 of the note transport path 95, and elongated grooves 95 areformed between adjacent guide projections 95 a. These guide projections95 a and the elongated grooves 95 b form a top plate 950 of the casingmain body 91 as a transport path for the bank note M.

[0037] The plurality of elongated grooves 95 b are formed with notchesin their front and rear positions, through which notches top parts oftransport rollers 95 c project. On the other hand, a pair of front andrear auxiliary rollers 95 d facing the transport rollers 95 c areprovided on the rear surface of the lid 92. The bank note M insertedinto the note transport path 95 passes through the note transport path95 by the rotation of the transport rollers 95 c while being tightlyheld between the transport rollers 95 c and the auxiliary rollers 95 dand is discharged to the outside through the rear end of the notetransport path 95.

[0038] A display lamp assembly 98 is provided at a front position of thetop of the lid 92. The display lamp assembly 98 is comprised of a readylamp 98 a for displaying whether the discriminating apparatus 1 is in anoperable state, a success lamp 98 b for displaying whether adiscrimination result on genuineness of the bank note M is a success,and a failure lamp 98 c for displaying whether the discrimination resulton genuineness of the bank note M is a failure. The ready lamp 98 a isturned on by turning the power switch 96 on, thereby showing that theapparatus main body 2 is in a state capable of discriminating. While theapparatus main body 2 is undergoing a discrimination process, this readylamp 98 a is turned off, thereby letting an operator know that he shouldnot insert a next bank note until the ready lamp 98 a is turned onagain.

[0039] As shown in FIGS. 3 to 6, the apparatus main body 2 includes asensor unit 20 constructed by integrally making light detecting elementsand a light emitting element to be described later, optical members,printed circuit boards into a module; a roller member 3 provided in thecasing main body 91; and a sensor casing 4 which is so provided in thelid 92 as to face the outer circumferential surface of the roller member3 and on which various sensors, circuit boards, etc. are mounted.

[0040] The roller member 3 serves as one of electrodes to which analternating voltage from an alternating-current power supply 30 (seeFIG. 5) is applied, and is comprised of a metallic center axis 31extending in widthwise direction and rotatably supported about itslongitudinal axis on specified bearings provided in the casing main body91, a metallic disk 32 concentrically and integrally fixed to the centeraxis 31, an insulating ring 33 made of a material having a highpermittivity such as barium titanate (BaTiO₃) and concentricallypressingly fitted on the metallic disk 32, and a metallic ring 34pressingly fitted on the insulating ring 33 and having an outercircumferential surface held in direct contact with the bank note M.

[0041] A lead plate 35 is adopted as the other electrode to which thealternative voltage is applied. This lead plate 35 is comprised of aflat lead plate main body 35 a and an electrode piece 35 b formed bybending a front end portion of the lead plate main body 35 a downward.An alternating-current electromagnetic field is created in the notetransport path 95 by applying an alternating voltage from thealternating-current power supply 30 to the roller member 3 and the leadplate 35 with the bank note M introduced to the note transport path 95.

[0042] On the other hand, a rectangular roller fitting window 91 a (seeFIG. 2) is formed in a center position of the top plate 950 of thecasing main body 91, and the metallic ring 34 of the roller member 3projects to the outside through this roller fitting window 91 a. Theroller member 3 is biased upward by a biasing force from anunillustrated biasing means, whereby the top thereof is located abovethe guide projections 95 a.

[0043] A pattern of stripes extending in the axis and having a specifiedpitch is formed on the entire outer circumferential surface of themetallic ring 34, and a photoreflector 36 is provided in vicinity of theroller member 3. This photoreflector 36 is so constructed as to projecta light onto the outer circumferential surface of the metallic ring 34and receive the reflected light, and detects a rotating speed of theroller member 3 by detecting a change of the reflected light caused bythe stripe pattern.

[0044] The sensor casing 4 is comprised of a casing main body 41 whichis square in plan view and has a specified thickness, and afunnel-shaped portion 42 continuously formed below the casing main body41 and having the shape of an inverted truncated rectangular pyramid. Onthe other hand, a rectangular window 92 b (see FIGS. 2 and 5)corresponding to the funnel-shaped portion 42 is formed in a bottomplate 92 a of the lid 92. In the inner surfaces of the rectangularwindow 92 b are formed slanted edge portions 92 c corresponding to theinclination of the surrounding wall surfaces of the funnel-shapedportion 42 as shown in FIG. 5. The sensor casing 4 fitted into therectangular window 92 b from above is mounted in the lid 92 while havingits bottom surface exposed to the outside by the engagement of thesurrounding wall surfaces of the funnel-shaped portion 42 with theslanted edge portions 92 c.

[0045] The sensor casing 4 has a substrate mounting recess for mountinga substrate 5 to be described later formed in its upper surface of thecasing main body 41 while having a glass substrate mounting recess 44for mounting a glass substrate 6 to be described later formed in itsbottom surface of the funnel-shaped portion 42. A portion correspondingto an optical path between the respective recesses 43, 44 is cut away tocommunicate the recesses 43, 44, thereby forming a pair of optical-pathholes 45 (first optical-path hole 45 a on the left side and a secondoptical-path hole 45 b on the right side) rectangular in plan view. Alight having passed through the glass substrate 6 propagates to thebottom of the substrate 5 through this optical-path hole 45.

[0046] Further, a LED mounting hole 46 for mounting a LED 54 to bedescribed later is formed in a position at the bottom of the substratemounting recess 43 and on the right side of the optical-path holes 45. Alower part of this LED mounting hole 46 communicates with the glasssubstrate mounting recess 44. Accordingly, a light from the LED 54 isincident on the glass substrate 6 through the LED mounting hole 46 andis reflected at a specified position (projection spot P (see FIG. 6) tobe described later) to be projected toward the rear surface of thesubstrate 5.

[0047] A lead plate mounting recess 47 for mounting the lead plate 35 isprovided in the funnel-shaped portion 42 in a position adjacent to therear part of the glass substrate mounting recess 44. The electrode piece35 b of the lead plate 35 is fitted in this lead plate mounting recess47 and is fixed by means of a screw or the like. The electrode piece 35b is so dimensioned that its bottom end faces the top plate 950 (seeFIG. 2) of the casing main body 91 with the lead plate 35 mounted on thesensor casing 4.

[0048] The substrate 5 is used to apply a specified electricalprocessing to outputs of light detecting devices 51 mounted on its rearsurface and to enable wiring, etc. for supplying a power to the LED 54.Light detecting devices 51 are arranged in a section of the substrate 5corresponding to the optical-path holes 45 of the sensor casing 4, andthe LED (light-emitting diode) 54 as a light emitting element isprovided in a section of the substrate 5 corresponding to the LEDmounting hole 46.

[0049] The light detecting devices 51 include a first light detectingdevice 52 provided in a left-side position on the rear surface of thesubstrate 5 so as to correspond to the first optical-path hole 45 a, anda second light detecting device 53 provided adjacent to the first lightdetecting device 52 so as to correspond to the second optical-path hole45 b. A first and a third light detecting elements 521, 522 are providedon the bottom surface of the first light device 52, and a second lightdetecting element 531 is provided on the bottom surface of the secondlight detecting device 53.

[0050] The first and third light detecting elements 521, 522 are adaptedto detect a light from an electroluminescent material having acharacteristic of emitting a light in an alternating-currentelectromagnetic field, i.e. a so-called electroluminescent light. Inorder to detect such an electroluminescent light, a band-pass filter 52a for causing only the electroluminescent light to transmit and cuttingother lights is placed on the front surface of the first light detectingdevice 52. Only the electroluminescent light can be made incident on thefirst light detecting device 52 by the presence of this band-pass filter52 a.

[0051] The first light detecting element 521 detects a light emittedfrom an electroluminescent ink portion M31 of a security mark M3 (seeFIGS. 7 and 8A as well as 8B) on the bank note M as described later,whereas the second light detecting element 531 detects a reflected lightfrom a usual ink portion M32 of the security mark M3. Further, the thirdlight detecting element 522 detects a light from the monitor mark M4 onthe bank note M.

[0052] The second light detecting elements 531 detects visible raysemitted from the LED 54 (LED light) and reflected by the surface of thebank note M, and a wavelength range of the light to be detected is wide.Accordingly, no such band-pass filter 52 a placed on the first lightdetecting element 521 is placed on the front surface of the second lightdetecting element 531. In this embodiment, the wavelength of the lightemitted from the LED 54 is differed from that of the electroluminescentlight by way of precaution.

[0053] As shown in FIG. 6, the substrate 6 is made of a first glasssubstrate 61 pentagon in front view (when the glass substrate 6 isviewed in a direction of +Y), a parallelogrammatic second glasssubstrate 62 placed on the left side of the first glass substrate 61,and a trapezoidal third glass substrate 63 placed on the left side ofthe second glass substrate 62.

[0054] As shown in FIGS. 3 and 6, the right surface of the first glasssubstrate 61 is formed into a slanted surface 61 a inclined downward at45° to the right with respect to a horizontal surface, and the leftsurface thereof is formed parallel to this slanted surface 61 a. A lightemitted from the LED 54 is perpendicularly incident on the slantedsurface 61 a.

[0055] Both left and right surfaces of the second glass substrate 62 areformed parallel to the slanted surface 61 a. The right surface of thethird glass substrate 63 is formed parallel to the slanted surface 61 aand the left surface thereof is formed into a perpendicular surface. Theglass substrate 6 having a trapezoidal shape as a whole is formed byplacing the first to third glass substrates 61, 62, 63 in widthwisedirection. The solid shape of such a glass substrate 6 is set so that itis pressed into the glass substrate mounting recess 44 of the casingmain body 41. Once fitted in, the glass substrate 6 is locked therein byaction of a frictional force.

[0056] A first dielectric multi-layer film 64 formed by depositing adielectric material such as titanium oxide is formed on the left surfaceof the first glass substrate 61 or the right surface of the second glasssubstrate 62, and a second dielectric multi-layer film 65 is formed onthe left surface of the second glass substrate 62 or the right surfaceof the third glass substrate 63. The composition and thickness of thefirst dielectric multi-layer film 64 are set so that the film 64 causeslights having a wavelength of the light emitted from the LED 54 totransmit and reflects lights having other wavelengths. Contrary to this,the composition and thickness of the second dielectric multi-layer film65 are set so that the film 65 reflects at least electroluminescentlights.

[0057] The first and second light detecting elements 521, 531 are soarranged that the light emitted from the LED 54 acts as follows. Thelight emitted from the LED 54 propagates toward the bottom surface ofthe second glass substrate 62 and is then diffusely reflected at theprojection spot P (see FIG. 6) on the surface of the bank note M beingheld in sliding contact with the bottom surface of the second glasssubstrate 62. Vertical components of the diffusely reflected lightpropagating upward are detected by the second light detecting device531, and vertical components of the electroluminescent light created onthe bank note M at the projection spot P are reflected at right anglesby the first dielectric multi-layer film 64 to become horizontalcomponents. The electroluminescent light horizontally propagating to theleft is reflected at right angles by the second dielectric multi-layerfilm 65 to propagate upward and to be detected by the firstlight-detecting device 521.

[0058] Vertical components of the electroluminescent light created onthe bank note M at a position (monitor spot P1) slightly leftward fromthe projection spot P are reflected at right angles by the firstdielectric multi-layer film 64 to become horizontal components and theelectroluminescent light horizontally propagating to the left arefurther reflected at right angles by the second dielectric multi-layerfilm 65 to propagate upward, and detected by the third light detectingelement 522 after being refracted by a lens member to be describedlater.

[0059] ITO films 66 formed by depositing ITO (indium-tin-oxide) which isan oxide of an indium-tin alloy are formed on the rear surface of theglass substrate 6 in contact with the bank note M and the vertical rightsurface thereof. Another electrode for creating an alternating-currentelectromagnetic field in the note transport path 95 is formed by the ITOfilms 66 (one electrode is formed by the insulating ring 33 of theroller member 3). Particularly on the rear surface of the glasssubstrate 6, a strong transparent insulating film 67 made of an aluminacoating or a diamond coating is further placed on the ITO film 66. Thepresence of this transparent insulating film 67 prevents the ITO film 66from being damaged by abrasion of the bottom of the glass substrate 6.Further, the transparent insulating film 67 prevents the ITO film 66 andthe metallic ring 34 from coming into direct contact when no bank noteis present in the note transport path 95, thereby preventing anoccurrence of electrical shorting.

[0060] In this embodiment, a lens member 68 and a mask 69 for coveringthe bottom surface of the lens member 68 are provided between the glasssubstrate 6 and the first and second light detecting devices 52, 53 asshown in FIGS. 3, 5 and 6.

[0061] The lens member 68 is made of a glass or transparent plastic.Although the lens member 68 is made of a glass in this embodiment, thepresent invention is not limited to the lens member 68 made of a glass.It may be made of a synthetic resin. Such a lens member 68 is adapted togather the lights from the projection spot P and the monitor spot P1 tothe respective light detecting elements 521, 522, 531 to increaseamounts of light detected thereby and is comprised of a glass plate 68 arectangular in plan view, a first convex lens 68 b bulging from theglass plate 68 a and facing the first light detecting element 521, and asecond convex lens 68 c facing the second light detecting element 531.Radii of curvature of the first and second convex lenses 68 b, 68 c areso set that the focusing planes thereof are located on the first andsecond light detecting elements, respectively.

[0062] The mask 69 is adapted to cut unnecessary ones of the lightspropagating toward the first and second light detecting devices 52, 53via the lens member 68 from the glass substrate 6.

[0063] In this embodiment, the first detecting construction 71 (see FIG.5) for detecting the security mark M3 printed using theelectroluminescent ink containing the electroluminescent material isconstructed by the alternating-current power supply 30, the rollermember 3, the lead plate 35, the glass substrate 6, the first convexlens 68 b and the first light detecting device 521, and the seconddetecting construction 72 (see FIG. 6) for detecting the usual inkportion M32 printed on the electroluminescent ink or near theelectroluminescent ink using the usual ink is constructed by the LED 54,the glass substrate 6, the second convex lens 68 c and the second lightdetecting device 531. Further, the third detecting construction 73 isconstructed by the alternating-current power supply 30, the rollermember 3, the lead plate 35, the glass substrate 6, the first convexlens 68 b and the third light detecting element 522.

[0064] According to the present invention, a light intensity detected bythe third detecting construction 73 is corrected based on a differencebetween it and a reference light intensity set beforehand, and thegenuineness of the bank note M is discriminated based on the correctedlight intensity. Before describing such a correction of the lightintensity, printing made on the bank note M to be discriminated isdescribed. FIG. 7 is a perspective view showing an exemplary printedstate of the bank note M. FIG. 8A is an enlarged section along C-C ofFIG. 7.

[0065] The security mark M3 and the monitor mark M4 as well as amultitude of various characters, figures and/or symbols are printed onthe surface of the bank note M. In an example of FIG. 7, the securitymark M3 is formed by a letter “S” and a “horizontal bar” intersectingwith the letter “S”. The bank note M inserted into the note transportpath 95 (see FIG. 1) of the discriminating apparatus 1 is pulled towardthe back of the note transport path 95 by the rotation of the transportrollers 95 c (see FIG. 2), and a portion of the bank note M indicated byphantom line in FIG. 7 is successively scanned by a relative movement ofthe light detecting devices 51 with respect to the bank note M.

[0066] Specifically, the light projected onto the projection spot P (seeFIG. 6) of the bank note M from the LED 54 and reflected by the surfaceof the bank note M is detected by the second light detecting element 531as time passes, and the light emitted from the electroluminescent ink atthe projection spot P caused by the inside of the note transport path 95becoming an alternating-current electromagnetic field is detected by thefirst light detecting device 521 as time passes. Further, the lightemitted from the electroluminescent ink at the monitor spot P1 isdetected by the third light detecting element 522 as time passes. Thegenuineness of the bank note M is discriminated by the control unit 8based on the detection results of the first and second light detectingdevices 52, 53.

[0067] Such a bank note M is, as shown in FIG. 8A, comprised of a basesheet M1, a coating layer M2 formed on the outer surface of the basesheet M1 by applying coating of a specified coating material in order tosmoothen a printing surface, the security mark M3 formed by applyingprinting to the surface of the coating layer M2 and the monitor mark M4provided near the security mark M3. The security mark M3 is formed in aposition corresponding to the projection spot P, and the monitor spot M4is formed in the shape of a straight line extending in forward andbackward directions so as to correspond to the horizontal bar of thesecurity mark M3 in a position corresponding to the monitor spot P1.

[0068] The security mark M3 is made of the electroluminescent inkportion M31 printed by the electroluminescent ink and the usual inkportion M32 formed by applying the usual printing ink on theelectroluminescent ink portion. An ink which causes theelectroluminescent light to transmit and has a wavelength different fromthat of the electroluminescent light is adopted as the ink of the usualink portion M32.

[0069] When the bank note M having a security mark M3 formed thereon isinserted into the note transport path 95 of the discriminating apparatus1, the unillustrated sensor detects it and the roller member 3 and thelead plate 35 in the note transport path 95 are set in an environment ofan alternating-current electromagnetic field by power supply from thealternating-current power supply 30 in response to sensor detection, andthe LED 54 emits a light. In this state, the bank note M is introducedbetween the metallic ring 34 of the roller member 3 and the glasssubstrate 6 by the rotation of the transport rollers 95 c (see FIG. 6)and passes through the note transport path 95 while being held insliding contact therewith, thereby being scanned by the light detectingdevices 51.

[0070] When the security mark M3 and the monitor mark M4 (see FIGS. 7and 8A) of the bank note M reach the projection spot P and the monitorspot P1 (see FIG. 6) in the note transport path 95 during scanning, themonitor mark M4 and the electroluminescent ink portion M31 emit theelectroluminescent lights since the environment of thealternating-current electromagnetic field is set at these positions. Theelectroluminescent light emitted from the monitor mark M4 propagates ina zigzag manner by being reflected by the first and second dielectricmulti-layer films 64 and 65 of the glass substrate 6 to be detected bythe third light detecting device 522 via the first convex lens 68 b.Further, the electroluminescent light from the electroluminescent inkportion M31 likewise propagates in a zigzag manner in the glasssubstrate 6 to be detected by the first light detecting element 521 viathe first convex lens 68 b

[0071] On the other hand, the light emitted from the LED 54 is projectedonto the usual ink portion M32 of the security mark M3 at the projectionspot P after transmitting through the first dielectric multi-layer film64, and vertically reflected components thereof are detected by thesecond light detecting element 531.

[0072]FIG. 8A is an enlarged section along C-C of FIG. 7, FIG. 8B is ananother embodiment of an enlarged section of FIG.7, essentially FIG. 8Awith M4 monitor mark elided. FIG. 8C shows a state where printing ismade by a mixed ink obtained by mixing the electroluminescent ink withthe usual nonluminescent ink.

[0073] Where the printed protuberant portion M3 (see FIGS. 7, FIG. 8A,FIG. 8B, FIG. 8C) of the bank note M reaches the projection spot P (seeFIG. 6) in the note transport path, the electroluminescent ink portionM31 (See FIG. 8B) or the electroluminescent ultrafine particles M31′(see FIG.8C) emit a light since the environment of the alternatingcurrent electromagnetic field is set at this position. The emittedelectroluminescent light propagates at a zigzag manner by beingreflected by the first and second dielectric multi-layer film 64 and 65of the glass substrate 61 to be detected by the first light detectingelement 52 (see FIG. 6). Further a light from the LED 54 is projectedonto the usual ink portion M32 or the ink base M32′ at the same positionas above after transmitting through the first dielectric multi-layerfilm 64, and the vertical components of the reflected light are detectedby the second light detecting element 53.

[0074]FIGS. 9A and 9B show changes of output values in proportion toamounts of light detected by the first, second and third light detectingelements 521, 531 and 522 over time during the scanning by the lightdetecting devices 51, wherein FIG. 9A is a partial enlarged view of thebank note M and FIG. 9B is a graph showing changes of the output valuesof the respective light detecting elements over time. In FIG. 9A, thebank note M is inverted from the state of FIG. 7 in order to conform tochanges of the output values over time shown in FIG. 9B. Thus, upper andlower sides of FIG. 9A correspond to left and right sides of FIG. 7.

[0075] The graph of FIG. 9B shows a change of the output values of thefirst light detecting element 521 corresponding to theelectroluminescent ink portion M31 over time at its upper part, a changeof the output values of the second light detecting element 531corresponding to the usual ink portion M32 over time at its middle partand a change of the output values of the third light detecting element522 corresponding to the monitor mark M4 over time at its lower part,respectively.

[0076] In FIG. 9A, the bank note M is moved to left, whereby theelectroluminescent light from the monitor mark M4 set slightly longerthan the electroluminescent ink portion M31 of the security mark M3 isfirst detected by the third light detecting element 522, theelectroluminescent light from the electroluminescent ink portion M31 isthen detected by the first light detecting element 521 and then thelight emitted from the LED 54 and reflected by the usual ink portion M32is detected by the second light detecting element 531. Thereafter, thefirst and second light detecting elements 521, 531 alternately andrepeatedly make detections depending on which of the electroluminescentink portion M31 or the usual ink portion M32 is located at theprojection spot P. During this time, detection of the third lightdetecting element 522 is continued for a period between t₁ and t₂.

[0077] In this embodiment, the electroluminescent ink portion M31 isprinted using an electroluminescent ink powder which is transparent invisible rays having the same reflectance as the base sheet of the banknote M, whereas the usual ink portion M32 is printed using a printingink which has a denser color than the base of the bank note M and doesnot transmit the electroluminescent light. Accordingly, if the bank noteM is placed in the environment of the alternating-currentelectromagnetic field, the electroluminescent ink portion M31 emits ablue light having a wavelength of, e.g. 450 nm, but this blue light isnot emitted to the outside by being hindered by the usual ink in aportion thereof over which the usual ink portion M32 is formed.

[0078] The light emitted from the LED 54 becomes a negative reflectedlight at the usual ink portion M32 (i.e. light intensity of thereflected light is lower than that of the reflected light from the baseof the bank note M since being denser than the base of the bank note M).Accordingly, as shown in FIG. 9B, the output values of the first andsecond light detecting elements 521, 531 change over time in the samemanner during a period between t₁ and t₂.

[0079] The change of the output value of the first light detectingelement 521 over time (first pattern) and that of the second detectingelement 531 over time (second pattern) are compared with the patterns ofthe genuine bank note set beforehand in the control unit 8, the banknote M scanned by the discriminating apparatus 1 is discriminated to begenuine when a correlation between the first and second patterns and thecorresponding patterns of the genuine bank note M is equal to or largerthan a predetermined value.

[0080] Accordingly, in order to compare the first and second patterns ofthe bank note M being discriminated with those of the genuine bank note,it is a condition that the respective patterns of the genuine bank notesM do not largely vary. In the actual genuine bank notes M, the colortone of the security marks M3 may change depending on printingfactories, printing apparatuses even if they are printed at the sameprinting factory, temperature and humidity variations and how long thebank notes have been used, etc. Under such circumstances, it isdifficult to highly precisely discriminate the genuineness of the banknotes M. Particularly, a percentage of discriminating the genuine banknotes as counterfeit increases, which may lead to a fall in reliabilityof the discriminating apparatus 1.

[0081] Accordingly, in the present invention, the monitor mark M4 is soprovided on the bank note M as to correspond to the security mark M3,and the output value corresponding to the electroluminescent ink portionM31 is corrected and converted into a standard one based on the outputvalue of the third light detecting element 522.

[0082] The above arrangement is made for the following reason.Specifically, even if printing conditions and working conditions for thesecurity mark M3 change, a variation of the printed state and avariation of color fading caused by the duration of use also occur tothe monitor mark M4. Accordingly, by scanning the monitor mark M4 whenthe bank note M is scanned by the discriminating apparatus 1 andcorrecting an output value corresponding to the electroluminescent inkportion M31 of the security mark M3 so as to conform it to a referenceoutput value of the genuine bank note, the security mark M3 can beconstantly returned to a state where the variations of the printed stateand the color fading are corrected. This solves a problem ofdiscriminating a genuine bank note to be counterfeit.

[0083]FIG. 9C is a graph showing changes of output values in proportionto amounts of light detected by the first and second light detectingelements 52, 53 during the scanning by the light detecting elements 51as time passes. This graph assumes a state where a center part of theletter “S” of FIG. 7 was scanned. A curve at the bottom of the graph isobtained by the first light detecting element 52, whereas the one at theupper part of the graph is obtained by the second light detectingelement 53. As can be seen from this graph, during a period between t₀and t₁ during which the printed protuberant portion M3 is not scanned bythe light detecting elements 51, the reflected light of the light fromthe LED 54 is detected only by the second light detecting element 53since the surface of the bank note M has a basic color. Accordingly, anoutput in conformity with an amount of the reflected light is sent fromthe second light detecting element 53, whereas an output value from thefirst light detecting element 52 is “0”.

[0084] On the other hand, the electroluminescent ink portion M31 emits alight during a period between t₁ and t₂ during which the printedprotuberant portion M3 is scanned. This emitted electroluminescent lightis detected by the first light detecting element 52, and the lightprojected from the LED 54 and reflected by the printed protuberantportion M3 is detected by the second light detecting element 53. Thus,detection signals are outputted from both the first and the second lightdetecting elements 52, 53. Specifically, patterns of the output valuesof the respective light detecting elements 52, 53 with the lapse of timeshould be substantially equal since the printed protuberant portion M3formed by applying the usual ink on the electroluminescent ink isscanned during the above period (t₁ to t₂). In the present invention,genuineness of the bank note M is discriminated by calculating theidentity of these patterns (degree of identity is called correlation) bya specified calculation processing.

[0085] The electroluminescent ink forming the electroluminescent inkportion M31 or electroluminescent ultrafine particles fundamentallyemits a light in the environment of the alternating-currentelectromagnetic field, and has a property of creating a reflected lighthaving a wavelength different from the light reflected by the usual inkforming the usual ink portion M32 or the ink base M32′ also when a lightfrom the LED 54 is projected thereto. Accordingly, even if the bank noteM is not placed in the environment of the alternating-currentelectromagnetic field, two kinds of reflected lights can be obtainedfrom the printed protuberant portion M3 by projecting the light from theLED 54 onto the surface of the bank note M, thereby enablingdiscrimination of genuineness described with reference to the graph ofFIG. 9C.

[0086]FIG. 10A is a block diagram showing one embodiment of a control ofcorrecting the output value corresponding to the electroluminescent inkportion M31 of the security mark M3 by the control unit 8. As shown inFIG. 10A, the genuineness discriminating control for the bank note M andthe drive control of the discriminating apparatus 1 are executed by thecontrol unit 8 provided internally with a CPU (central processing unit)80. With the CPU 80 are connected a RAM (random access memory) 81 and aROM (read only memory) 82.

[0087] The RAM 81 is an external storage device in and from which datacan be freely written and read, and output values from the first andsecond light detecting elements 52, 53 with the lapse of time, resultsof specified calculation processings are inputted to the RAM 81 and, ifnecessary, various values including results of intermediate processingsand calculations are outputted therefrom. The ROM 82 is an externalstorage device exclusively for reading purpose, and a program forperforming a correction calculation for the electroluminescent inkportion M31 of the security mark M3 is stored in advance. Uponapplication of a power to the discriminating apparatus 1 by operatingthe power switch 96, the program in the ROM 82 is transferred to the CPU80.

[0088] Every time the bank note M is inserted into the note transportpath 95, the CPU 80 outputs drive signals to various devices andcorrects the output value of the first light detecting element 521corresponding to the electroluminescent ink portion M31 of the bank noteM to be discriminated based on the output value (light intensity) of thethird light detecting element 522 corresponding to the monitor mark M4in accordance with the program. A LED control circuit 54 a is providedbetween the control unit 8 and the LED 54. This LED control circuit 54 acontrollably turns the LED 54 on and off in accordance with a controlsignal from the control unit 8. Specifically, a control is executed toturn the LED 54 on when the unillustrated sensor detects insertion ofthe bank note M into the note transport path 95 and to turn the LED 54off when the bank note M passes the note transport path 95.

[0089] A first amplifier 521 a and a first analog-to-digital (A/D)converter 521 b are provided in series between the first light detectingelement 521 and the control unit 8; a second amplifier 531 a and asecond A/D converter 531 b are provided in series between the secondlight detecting element 531 and the control unit 8; and a thirdamplifier 522 a and a third A/D converter 522 b are provided in seriesbetween the third light detecting element 522 and the control unit 8.The respective amplifiers 521 a, 531 a, 522 a amplify feeble detectionsignals from the first, second and third light detecting elements 521,531, 522 and the respective A/D converters 521 b, 531 b, 522 b convertanalog signals from the amplifiers 521 a, 531 a, 522 a into digitalsignals.

[0090] Further, power is supplied to the roller member 3 and the leadplate 35 from the alternating-current power supply 30 via an inverter37. The inverter 37 converts an alternating voltage supplied from thepower supply 30 into an alternating voltage having a specified voltagevalue and a specified frequency and supplies it to the roller member 3and the lead plate 35. The inverter 37 is turned on and off inaccordance with a control signal from the CPU 80 and sets the voltagevalue and frequency when being turned on.

[0091] The output values of the first, second and third light detectingelements 521, 531, 522 thus processed are inputted to the control unit 8after being digitized. The CPU 80 applies a specified calculation to thereceived output values to correct the digital output values of the firstand second light detecting elements 521, 531 according to the digitaloutput value of the third light detecting element 522, and discriminatesthe genuineness of the bank note M based on the corrected output values.

[0092] In order to perform such a processing, the CPU 80 is providedwith a light intensity comparing means 80 a for comparing the digitaloutput value (light intensity) from the third light detecting element522 with a reference light intensity stored beforehand in the RAM 81,and a light intensity converting means 80 b for correcting the outputvalues of the first and second light detecting elements 521, 531 basedon a comparison result of the light intensity comparing means 80 a andconverting them into corrected output values. The CPU 80 is alsoprovided with genuineness discriminating means 80 c for discriminatingthe genuineness of the bank note M. This genuineness discriminatingmeans 80 c is so constructed as to discriminate genuineness by means ofa specified calculation based on the output values of the first andsecond light detecting elements 521, 531 which were obtained by scanningthe bank note M and corrected by the light intensity converting means 80b. The light intensity comparing means 80 a, the light intensityconverting means 80 b and the genuineness discriminating means 80 c aredescribed in detail later with reference to FIG. 12A.

[0093] The discrimination result on the genuineness of the bank note Mby the genuineness discriminating means 80 c is outputted to the displaylamp assembly 98, and the genuineness of the bank note M having passedthrough the note transport path 95 can be visually confirmed by seeingwhich of the success lamp 98 b and the failure lamp 98 c is on. Further,it can be confirmed by seeing the ready lamp 98 a turned on that thecertified paper discriminating apparatus 1 can receive the bank note M.

[0094] The control unit 8 is also provided with a drive control circuit84 for outputting drive signals to various devices (the transportrollers 95 c, unillustrated flappers, etc.) provided in thediscriminating apparatus 1. The devices provided at the specifiedpositions in the discriminating apparatus 1 operate while linking witheach other in accordance with control signals sent from the control unit8 via the drive control circuit 84.

[0095] A detection signal representing the rotating speed of the rollermember 3 (specifically the number of stripes provided on the outercircumferential surface of the metallic ring 34 passing a detectingposition per unit time) is inputted from the photoreflector 36 to thecontrol unit 8, and a timing pulse corresponding to this input value issent to the respective A/D converters 521 b, 531 b, 522 b via anunillustrated timing pulse generating circuit, as later shown in FIG.10B. This timing pulse generating circuit sends so-called timing signalsrepresenting specified periods used in converting an analog signal intoa digital signal to the A/D converters 521 a, 531 aand 522 a. A firstanalog value or an average analog value during the period defined by thetiming signal is converted into a digital value.

[0096] In an alternative embodiment FIG. 10B a time pulse generatingcircuit 83 connects to 522B, 521B. 80C, a genuineness comparing means ofFIG. 10A is omitted from the CPU 80 of FIG. 10B. The photoreflector 36of 10A is not shown from FIG. 10B. A roller member 3 of FIG. 10A is notshown in FIG. 10B.

[0097] Next, the genuineness discrimination for the bank note Mperformed in the control unit 8 is described with reference to FIGS. 11Aand 12A. FIG. 11B is an alternative embodiment of a flow chart showing adata sampling routine executed to store data on intensities of thelights detected by the light detecting elements. FIG. 11A is a flowchart showing a data sampling routine for scanning the surface of thebank note M by the light detecting devices 51, and FIG. 12A is a flowchart showing a correlation calculation routine for discriminating thegenuineness of the bank note M based on the scanned data.

[0098] First, a procedure of storing photoelectrically converted outputsignals from the light detecting devices 51 (analog signals representingdetections by the first and second light detecting elements 521, 531) ina specified storage device of the control unit 8 or the RAM 81 isdescribed with reference to FIG. 11A. When the data sampling routine isstarted in Step S1, the CPU 80 calls the program stored in the ROM 82,starts implementing it and initializes the respective mechanisms(registers, counters, flappers, etc.) in accordance with the program(Step S2). Simultaneously, a control of the note transporting mechanismby the drive control circuit 84 is started. When this bank note M to bediscriminated is inserted into the note transport path 95 in this state,the unillustrated sensor detects it, the CPU 80 outputs a signal to thetransport rollers 95 c via the drive control circuit 84 to drive themand also outputs drive signals to the inverter 37 and the LED controlcircuit 54 a. Accordingly, a specified alternating voltage from thealternating-current power supply 30 is supplied to the roller member 3and the lead plate 35 to set the note transport path 95 in theenvironment of the alternating-current electromagnetic field (Step S3),and a turn-on signal is outputted from the LED control circuit 54 a toturn the LED 54 on (Step S4).

[0099] Subsequently, the bank note M inserted into the note transportpath 95 advances in the note transport path 95 by the rotation of thetransport roller 95 c to come into a clearance between the bottomsurface of the glass substrate 6 and the outer circumferential surfaceof the roller member 3, and the roller member 3 is rotated about thecenter axis 31. The rotating speed of the roller member 3 is detected inthe form of a pulse signal corresponding to the stripe pattern whichsignal is obtained by projecting a light onto the outer circumferentialsurface of the metallic ring 34 having the stripe pattern and receivinga reflected light by the photoreflector 36, and the analog output valuesof the first to third light detecting elements 521, 531, 522 areconverted into digital signals by the respective A/D converters 521 b,531 b, 522 b after being amplified by the first to third amplifiers 521a, 531 a, 522 a in synchronism with the pulse signal in accordance withcontrol signals from the CPU 80 based on the detection result (Step S5).

[0100] Amplification factors of the first to third amplifiers 521 a, 531a, 522 a are set at initial values in advance. An analog light intensity(i.e. light intensity of the monitor mark M4) from the initialized thirdamplifier 522 a is digitally converted into a monitor light intensityPD3 by the third A/D converter 522 b, and this monitor light intensityPD3 is compared with a reference light intensity th stored in the RAM 81beforehand (Step S6). The reference light intensity th is set at aminimum presumable value of the light intensity from theelectroluminescent ink portion M31 of the bank note M.

[0101] In Step S6, it is discriminated whether the monitor lightintensity PD3 is equal to or larger than the reference light intensityth. Step S7 and subsequent steps are carried out upon judgment that thethird light detecting element 522 is detecting the light emitted fromthe monitor mark M4 if PD3≧th, and a digital light intensity from thefirst light detecting element 521 (corresponding to theelectroluminescent ink portion M31) is stored as a data in the storagedevice after being converted into a corrected light intensity. On theother hand, if PD3<th, this routine returns to Step S3 after proceedingto Step S13 upon judgment that the third light detecting element 522 isnot detecting the light from the monitor mark M4 (i.e. the monitor markM4 is not present at the monitor spot P1).

[0102] In Step S7, the light intensity comparing means 80 a calculates adeviation of the monitor light intensity PD3 from the reference lightintensity th, and the light intensity converting means 80 b calculates aratio of this deviation to the reference light intensity th, which ratiois then set at an amplification factor (gain) (Step S8). Subsequently,the CPU 80 receives the outputs from the first and second lightdetecting elements 521, 531 at a timing of receiving the pulse signalfrom the photoreflector 36, and successively stores multiples of therespective output values by the above gain as corrected output values(the corrected output value from the first light detecting element 521as a first corrected output value PD1, and the corrected output valuefrom the second light detecting element 531 as a second corrected outputvalue PD2) in a specified storage device (e.g. RAM 81) (Step S10).

[0103] The above output values are stored as follows. Specifically, afirst working area for temporarily saving the first corrected outputvalue PD1 from the first light detecting element 521 and first storageareas the first corrected values PD1 are set beforehand in the storagedevice. For the digital signals from the second light detecting element531, a second working area for temporarily saving the second correctedoutput value PD2 and second storage areas D1(j)(j(storage address)=1 ton) for successively storing the second corrected output values PD2 arelikewise set beforehand in the storage device.

[0104] Every time the first and second corrected output values PD1, PD2are sent from the first and second light detecting elements 521, 531,the values thereof are successively (i=i+1, j=j+1) stored in the firstand second storage areas D1(i), D2(j) while successively shifting thestorage addresses by counting the pulse signals outputted from thephotoreflector 36 (Step S10 to S12). When the passage of the trailingend of the monitor mark M4 at the monitor spot P1 (see FIG. 6) isdetected based on the count result of the signals from thephotoreflectors 36 (Step S13), scanning of the bank note M is completedupon judgment that data sampling has been completed. In this way, thelight intensities of the security mark M3 scanned by the first andsecond light detecting 521, 531 are corrected into the first and secondcorrected output values PD1, PD2 based on the gain obtained by comparingthe monitor light intensity PD3 detected by the third light detectingelement 522 with the reference light intensity th, and the genuinenessof the bank note M is discriminated based on the corrected output valuesPD1, PD2 stored in the first and second storage areas D1(i), D2(j) whilesuccessively shifting the storage addresses. Thus, an inconvenience ofdiscriminating the genuine bank notes M to be counterfeit due to thevarying printed state of the ink of the security mark M3, color fadingcaused by the use of long duration, and other causes can be securelyprevented, thereby improving a rate of discriminating genuine bank notesM as genuine.

[0105]FIG. 11B shows the alternative embodiment of 11A with Step S1 thestart of a data sampling routine, Step S2 initialization, Step S3 emitLED, Step S4 convert AND, Step S5 query end?, Step 6 store data, Step 7(see Step 12 of 11B ) i.e. in the earlier step prior to Step 7 it isdiscriminated whether the monitor light intensity PD3 is equal to orlarger than the reference light intensity th the values thereof aresuccessively (i=i+1, j =j+1) stored in the first and second storageareas D1(i), D2(j) while successively shifting the storage addresses bycounting the pulse signals outputted from the photoreflector 36), Step 8end sampling and Step 9 end.

[0106] Upon completion of scanning of the bank note M, the correlationcalculation routine is executed to discriminate the genuineness of thebank note. This calculation is performed by the genuinenessdiscriminating means 80 c. This routine is described below withreference to FIG. 12A. At a stage where this routine is executed, ncorrected values of the light intensities from the first and secondlight detecting elements 521, 531 are stored in the first and secondstorage areas D1(i), D2(j), respectively.

[0107] Upon start of the correlation calculation (Step S20), the data inthe first and second storage areas D1(i) and D2(j) of the RAM 81 areread by the genuineness discriminating means 80 c (Step S21). Binaryprocessing is applied to the respective read data (Step S22).Subsequently, an absolute value Dn of a difference between the thusobtained binary data corresponding to each address is calculated, andthis operation is repeated for all the stored data (Step S23 to S25).

[0108] Upon completion of the above operation (YES in Step S25), a totalsum D of the absolute values Dn of the respective differences iscalculated (Step S26), and the total sum D is compared with a very smallvalue α set beforehand (Step S27). If D <a as a result of thiscomparison, the genuineness discriminating means 80 c discriminates thebank note M to be genuine upon judgment that the two patterns detectedby the first and second light detecting elements 521, 531 coincide (StepS28). On the other hand, if D>α, the bank note M is discriminated to becounterfeit (Step S29).

[0109] In order to further improve the precision of the genuinenessdiscrimination for the bank note M, calculation may be performed usingdata comprised of three or more digits. Further, not only the twopatterns (detection patterns of the electroluminescent ink portion M31and the usual ink portion M32 by the first and second light detectingelements 521, 531 over time (see FIG. 9B)) are compared, but they may bealso compared with specific patterns stored beforehand in the ROM 82 tomake a more precise discrimination on genuineness. In addition, the twopatterns may be compared by calculating ratios thereof instead ofcalculating differences between them.

[0110] As described in detail above, according to the present invention,the monitor mark M4 is used to measure a luminance (intensity of lightemission) of the light emitted from the electroluminescent ink, and aluminance of the light emitted from the electroluminescent ink portionM31 of the security mark M3 is corrected based on the luminance of thelight from the monitor mark M4. Accordingly, variation of light emissionfrom the electroluminescent ink portion M31 due to the state of inkduring printing, color fading caused by the use of long duration, etc.is solved, thereby improving precision of the genuinenessdiscrimination.

[0111] Although the special monitor mark M4 is provided for monitoringpurpose separately from the security mark M3 in the foregoingembodiment, it may be hidden in the security mark M3. Alternatively, aleading end portion of the security mark M3 may be used as the monitormark M4. In such a case, a luminance of the first electroluminescentlight from the security mark M3 may be stored and the detected lightintensity may be corrected based on the stored luminance. Thiseliminates the need for providing the special monitor mark M4.

[0112] Further, instead of changing the amplification factors of theamplifiers 521 a, 531 a, the same effect can be accomplished by changingan output voltage value and an oscillation frequency of a circuit of theinverter 37 of FIG. 10A. Furthermore, if a monitor mark is also set forthe usual ink and a reflected light therefrom is detected to detect achange in the state of ink due to, e.g. abrasion and color fading, andcorrection is accordingly made based on the detection result, an evenmore precise genuineness discrimination can be realized.

[0113] Although the electroluminescent light from the electroluminescentink portion M31 of the bank note M and the light emitted from the LED 54and reflected by the usual ink portion M32 are respectively detected bythe first and second light detecting elements 521, 531 in the foregoingembodiment, they may be both detected by one light detecting element anddata on the security mark M3 may be stored in the first and secondstorage areas D1(i) and D2(j). However, in this case, it is necessary toprovide a time shift between data sampling of the electroluminescentlight from the electroluminescent ink portion M31 and data sampling ofthe reflected light from the usual ink portion M32.

[0114] As shown in the alternate embodiment FIG. 12B of the correlationcalculation flow, at a stage where this routine is executed, n digitalsignals from the first and second light detecting elements 52, 53 arestored in the first and second storage areas D1(i), D2(j), respectively.

[0115] Upon start of the correlation calculation (Step S10), addresses(i=a to a+k) where the data detected by the first light detectingelement 52 for detecting the electroluminescent ink and stored in thefirst storage area D1(i) the values of which data are larger than apredetermined threshold value α are extracted (Step S11, i.e. extractaddress (i=a to a+k) where PD1,) Subsequently, addresses (=b to b+k) inthe second storage area D2(j) storing the data from the second lightdetecting element 53 and corresponding to the above addresses (i=a toa+k) are obtained (Step S12 essentially, extract the address where thePD2 data corresponding to the address (i=a to a+k) is stored) After a, bare newly replaced by i, j (Step S13), differences (AD 1 (i) and AD2(j)between the data in the adjacent addresses are calculated for the firstand second storage areas D1(i) and D2(j) (Step S14). By calculating suchdifferences, only the pattern printed on the bank note M can beeffectively detected by removing variations of the electroluminescentlight and the light from the LED which moderately changes during thetransport of the bank note M and sensitivity differences of the lightdetecting elements 51 and the circuits.

[0116] Subsequently, absolute values of the differences between AD1(i)and AD2(j) are successively calculated and stored in H(1) (Step S15).The above operation is repeated until i, j become larger than a+k, b+k,respectively (Steps S14 to S17). Values of H(1) are totaled uponcompletion of the repeated operations (Step S18). The correlationcalculating means 80 a (see FIG. 10A) is so constructed as to performthe operations of Steps S11 to S18).

[0117] The above total value is compared with a predeterminedgenuineness reference value ε and the bank note M is discriminated to begenuine if the total value is equal to or smaller than ε (Step S20)while being discriminated to be counterfeit if it is larger than ε (StepS21) and then this routine ends (Step S22). The genuinenessdiscriminating means 80 b is so constructed as to perform the operationsof Steps S19 to S21.

[0118] Hereinafter, a case where the electroluminescent light and thereflected light of the LED light are detected by one light detectingelement is described with reference to FIG. 13. FIG. 13 is a flow chartshowing one embodiment of the case where data sampling of the securityM3 is performed by one light detecting element. Although reference ismade to FIG. 10A for description based on FIG. 13 when necessary, thefirst and second light detecting elements 521, 531, the first and secondamplifiers 521 a, 531 a and the first and second A/D converters 521 b,531 b in FIG. 10A are replaced by one light detecting element, oneamplifier and one A/D converter in this embodiment. Reference is alsomade to other FIGURES when necessary if the elements of this embodimentare the same as those of the foregoing embodiment.

[0119] As shown in the flow chart of FIG. 13, when the data samplingroutine is started (Step S30), the CPU 80 starts implementing theprogram, initializes the respective devices, sets the transportmechanism to an operation standby state, and clears or initializesvarious counters, flags and registers (Step S31).

[0120] Subsequently, when the bank note M is inserted into the notetransport path 95, the sensor detects it and the CPU 80 outputs a signalto start the transport of the bank note M, a signal to the inverter 37to start oscillation and then a signal to the amplifier to set anamplification factor of the amplifier at a higher value to detect theelectroluminescent light (Step S33).

[0121] When the bank note M inserted into the note transport path 95(see FIG. 1) reaches the projection spot P (see FIG. 6), the rollermember 3 is rotated as the bank note M is transported, and a pulsesignal synchronizing with a transport speed of the bank note M isoutputted from the photoreflector 36 to the CPU 80. During this time,the amplifier amplifies the output of the light detecting element insynchronism with the pulse signal from the photoreflector 36 and the A/Dconverter digitizes the amplified signal (Step S34).

[0122] Subsequently, the output (monitor light intensity PD3) of thethird light detecting element 522 is compared with the reference lightintensity th stored beforehand in the RAM 81 (Step S35). If PD3≧th, thisroutine proceeds to Step S36 upon judgment that the third lightdetecting element 522 of FIG. 10A has detected the light emitted fromthe electroluminescent ink portion M31. Then, a gain is calculated andset as in the foregoing embodiment by comparing the monitor lightintensity PD3 and the reference light intensity th (Steps S36 and S37),and corrected output values PD corresponding to the electroluminescentink portion M31 corrected based on this gain are stored in the firststorage areas D1(i) (Step S39).

[0123] On the other hand, if PD3<th, operations of Steps S32 to S35 arerepeated after proceeding to Step S49 upon judgment that the third lightdetecting element 522 has not yet detected the electroluminescent light.

[0124] When the corrected output values PD are stored in the firststorage areas D1(i) in Step S39, the CPU 80 counts pulses outputted fromthe photoreflector 36 (Step S40) and outputs a signal to the inverter 37to stop of the oscillation of the alternating voltage from the circuitafter adding a variable 1 (Step S41). In this way, driving of theinverter 37 is stopped (Step S42). A flow up to Step S42 is for storingthe data on the light emitted from the electroluminescent ink portionM31 in the first storage areas D1(i).

[0125] Subsequently, a flow for storing the data on the light emittedfrom the LED 54 and reflected by the usual ink portion M32 in the secondstorage areas D2(j) is started in Step S44. Specifically, in order todetect the pattern of the usual ink portion M32, the CPU 80 outputs acontrol signal to the LED control circuit 54 a to thereby turn the LED54 on (Step S43). In this case as well, a gain is likewise set for theLED light detected by the light detecting element (Step S44), A/Dconversion is applied to the obtained amplified light intensity (StepS45) to calculate the corrected output values PD of the reflected light,which are successively stored in the second storage areas D2(j) (StepS46).

[0126] Subsequently, the CPU 80 counts pulses from the photoreflector 36(Steps S47, S48), discriminates the presence or absence of the pulseoutput from the photoreflector 36 during a predetermined period (StepS49). In the absence of the pulse output, this routine ends (Step S50)upon judgment that the transport of the bank note M has been completed.In the presence of the pulse output, this routine returns to Step S32 torepeat the succeeding operations.

[0127] By alternately detecting the light intensities corresponding tothe electroluminescent ink portion M31 and the usual ink portion M32according to the pulses from the photoreflector 36, data used todiscriminate genuineness can be stored in the first and second storageareas D1(i) and D2(j) although only one light detecting element is used.FIGS. 14A and 14B show another embodiment of the security mark, whereinFIG. 14A is a partial enlarged view of the bank note M and FIG. 14B isgraphs showing changes of output values from the respective lightdetecting elements over time. In this embodiment, as shown in FIG. 14A,a security mark M3′ is comprised of a second usual ink portion M33printed using a usual nonluminescent ink in addition to theelectroluminescent ink portion M3 and the usual ink portion M32 printedone over the other as in the foregoing embodiment. The second usual inkportion M33 is adjacent to the ink portions M31, M32 printed one overthe other along widthwise direction at a side opposite from the monitormark M4.

[0128] In an example shown in FIG. 14A, a letter of “C” of the usual inkportion M32 and a letter of “A” of the second usual ink portion M33 canbe seen, but a letter of “E” of the electroluminescent ink portion M31and the bar-shaped monitor mark M4 cannot be seen by the naked eye sincethey are printed using an electroluminescent ink having a spectralproperty similar to the reflection characteristic of the basic sheet ofthe bank note M.

[0129] On the other hand, a light detecting device 51′ is, as shown inFIG. 14A, provided with a fourth light detecting element 532 fordetecting a reflected light from the second usual ink portion M33 inaddition to the first to third light detecting elements 521, 531, 522 ofthe foregoing embodiment. By scanning such a security mark M3′ by thelight detecting device 51′, output values as shown in FIG. 14B can beobtained from the respective light detecting elements 521,522,531,532.

[0130] Specifically, a top graph of FIG. 14B shows a change of theoutput value of the reflected light from the second usual ink portionM33 detected by the fourth light detecting element 432 over time. In amiddle graph, the output values of the light emission from theelectroluminescent ink portion M31 detected by the first light detectingelement 521 are indicated by dotted line while the output values of thereflected light from the usual ink portion M32 detected by the secondlight detecting element 531 are indicated by solid line. A bottom graphshows a change of the output values of the light emission from themonitor mark M4 detected by the third light detecting element 522 overtime.

[0131] Precision in discriminating the genuineness of the bank note Mcan be further improved by providing the second usual ink portion M33printed using the usual nonluminescent ink as part of the security markM3′ in addition to the electroluminescent ink portion M31 and the usualink portion M32.

[0132] According to the present invention, the certified paper isprinted with the security mark using both the luminescent ink whichemits a light upon being placed in the specified environment and theusual nonluminescent ink, and/or the monitor mark used to monitor theprinted tone of the security mark in vicinity of the security mark usingthe luminescent ink. Thus, by scanning the monitor mark emitting a lightin the specified environment when letting the specified certified paperdiscriminating apparatus in which the reference light intensity isstored beforehand scan the security mark of the certified paper, theprinted tone of the security mark can be known by a comparison of thelight intensity of the scanned monitor mark with the reference lightintensity. Thus, a correction can be made based on the comparison resultof the scanned security mark, with the result that data on theintensities of the lights from the security mark can be standardized.

[0133] Accordingly, an inconvenience residing in the prior art thatprecision of discrimination of the certified paper based on the varyinglight intensity data from the scanned security mark is lower due to sucha variation can be solved, thereby improving precision in discriminatingthe genuineness of the certified paper.

[0134] Further, the monitor mark made of the luminescent ink of thecertified paper fed into the discriminating apparatus emits a light uponbeing placed in the specified environment, and this light emission isdetected by the third light detecting element. The light intensitycorresponding to the monitor mark detected by the third light detectingelement is compared with the reference light intensity set beforehand tocalculate the deviation by the light intensity comparing means, and theoutput value from the first light detecting element is converted intothe corrected output value corresponding to the deviation based on thecalculation result by the light intensity converting means. Thegenuineness of the certified paper is discriminated based on thecorrected output value by the genuineness discriminating means.

[0135] In this way, prior to discrimination of the genuineness of thecertified paper, an electrical signal representing a standard densityobtained by correcting the density of the luminescent ink of the printedmonitor mark is sent to the genuineness discriminating means, which thenmakes a specified genuineness discrimination. Thus, such aninconvenience that different printed states of the luminescent ink onthe certified papers influence a result of genuineness discriminationcan be solved, thereby constantly realizing a proper genuinenessdiscrimination.

[0136] Further, the environment of the alternating-currentelectromagnetic field created upon application of an alternating voltageis adopted as the specified environment and the electroluminescent inkwhich emits a light in the environment of the alternating-currentelectromagnetic field is adopted as the luminescent ink. Since theelectroluminescent ink is nonluminescent and colorless in a usualenvironment while emitting a light in the environment of thealternating-current electromagnetic field, the certified papers can benormally used without any trouble while the electroluminescent inkeffectively performs its function in discriminating genuineness.

[0137]FIG. 15 is a diagram showing another example of the arrangement ofthe first and second detecting elements.

[0138] Although the genuineness of the bank note M is discriminatedbased on the correlation of the output values from the first and secondlight detecting elements 52, 53 obtained by comparing them in theforegoing embodiments, such a discrimination may be instead made asfollows. Light detection patterns of the first and second lightdetecting elements 52, 53 over time for a genuine bank note M are storedbeforehand as reference patterns, light detection patterns of the firstand second light detecting elements 52, 53 over time and the referencepatterns stored beforehand are compared every time a bank note to bediscriminated is fed to the discriminating apparatus 1 to discriminatethe genuineness thereof, and the bank note is discriminated to begenuine when the patterns are assumed to be same within a specifiedpermissible range. In the case of adopting such a discriminating method,the control unit 8 is provided with a reference pattern storage forstoring reference light detection patterns of a genuine bank note, acomparing means for comparing the output values from the first andsecond light detecting elements 52, 53 and the reference patterns, and agenuineness discriminating means for discriminating the genuineness of acertified paper based on the comparison result of the comparing means.

[0139] Further, both the first and the second light detecting elements52, 53 are so constructed as to detect the light from the same position(projection spot P) of the bank note M in the foregoing embodiments.Instead, light detecting positions of the first and second lightdetecting elements 52, 53 may be spatially displaced in forward andbackward directions (advancing direction of the bank note M) as shown inFIG. 15. However, in this case, a spatial displacement needs to betemporally compensated. For example, light detection of the first lightdetecting element 52 may be caused to correspond to that of the secondlight detecting element 53 made after the lapse of a specified period.With this arrangement, the same effect as the one obtained when thefirst and second light detecting elements 52, 53 detect the light at thesame position can be obtained while avoiding an inconvenience ofarranging the first and second light detecting elements 52, 53 in anarrow place. respective light detecting elements over time,

[0140]FIG. 9C shows a graph showing changes of output values inproportion to amounts of light detected by first and second lightdetecting elements during scanning over time,

[0141]FIG. 10A is a block diagram showing one embodiment of a correctioncontrol for the output values corresponding to an el ink portion of asecurity mark,

[0142]FIG. 10B is a block diagram showing another embodiment of acorrection control for the output values corresponding to an el inkportion of a security mark,

[0143]FIG. 11A is a flow chart showing a data sampling routine executedto scan the surface of the bank note by the light detecting device,

[0144]FIG. 11B is another embodiment of a flow chart showing a datasampling routing,

[0145]FIG. 12A is a flow chart showing a correlation calculation routineexecuted to discriminate genuineness based on the scanned data,

[0146]FIG. 12B is another embodiment showing a correlation calculationroutine,

[0147]FIG. 13 is a flow chart showing another embodiment in which dataof the security mark are sampled by one light detecting element, and

[0148]FIGS. 14A and 14B are a diagram showing the security mark and anarrangement of the light detecting device suitable for detecting such asecurity mark, and graphs showing changes of the output values of therespective light detecting elements over time, respectively.

[0149]FIG. 15 is a diagram showing another example of arrangement of thefirst and second detecting elements.

1. A certified paper on which a security mark is printed which comprises: a luminescent ink which emits a light upon being placed in a specified environment and a usual nonluminescent ink; and a monitor mark to monitor a printed tone of the security mark which is printed in vicinity of the security mark using the luminescent ink.
 2. A certified paper on which a security mark is printed which comprises: a luminescent ink which emits a light upon being placed in a specified environment and a usual nonluminescent ink.
 3. A certified paper on which a security mark is printed which comprises: a monitor mark used to monitor a printed tone of the security mark which is printed in vicinity of the security mark using the luminescent ink.
 4. A certified paper discriminating apparatus for discriminating the genuineness of the certified paper according to claims 1 or 3 by scanning the certified paper in an extending direction of the monitor mark, comprising: a first light detecting means for detecting a light emitted from the luminescent ink of the security mark upon being placed in the specified environment, a second light detecting means for detecting a reflected light from the nonluminescent ink of the security mark, the first and second light detecting means being so arranged as to detect the lights from the same position of the certified paper, a third light detecting means for detecting a light emitted from the monitor mark, a light intensity comparing means for comparing a light intensity detected by said third light detecting means with a preset reference light intensity to calculate a deviation from the reference light intensity, a light intensity converting means for converting an output value from the first light detecting means into a corrected output value corresponding to the deviation; and a genuineness discriminating means for discriminating the genuineness of the certified paper based on the corrected output value.
 5. A certified paper discriminating apparatus according to claim 4 wherein the specified environment is an environment of an alternating-current electromagnetic field created upon application of an alternating voltage and a luminescent ink has an electroluminescent property of emitting a light in the environment of said alternating-current electromagnetic field.
 6. A certified paper discriminating means according to claim 4 wherein the correlation calculating means performs said calculation only when the output value from a light and a detecting means is equal to or larger than a predetermined threshold value.
 7. A certified paper discriminating apparatus for discriminating genuineness of certified papers to which printing is applied using both a luminescent ink which emits a light upon being placed in a specified environment and an usual printing ink, comprising: a first light detecting means for detecting a light emitted from the luminescent light being placed in the specified environment, a second light detecting means for detecting a reflected light from the usual ink whose wavelength is different from that of the light emitted from the luminescent ink, said first and said second light detecting means being so arranged as to detect a light from the same position on the certified papers, 